Connecting clamp, connecting apparatus and connecting method

ABSTRACT

A connecting clamp ( 4 ) comprises a heating member ( 9 ) which surrounds a portion to be connected of a steel pipe ( 1 ) and heats the portion to be connected, and a first clamp section ( 6 ) and a second clamp section ( 7 ) positioned on opposite sides of the portion to be connected and clamping the steel pipe, whereby the portion to be connected is connected by heating the portion to be connected by the heating member while applying pressure to the portion to be connected by the first and second clamp sections. The first and second clamp sections and the heating member are so arranged as to be slid around the outer surface of the steel pipe from one side of the steel pipe to the other side thereof.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a connecting clamp, connectingapparatus and connecting method, which are suitable for use at the timeof joining a portion to be connected of a rod-like member, such as ametal pipe, by using a diffusion bonding method. This invention alsorelates to an ultrasonic detecting method and ultrasonic detectingapparatus, which are effective in inspecting defects on a surface joinedby diffusion bonding. This application is based on Japanese PatentApplications No. Hei 11-228038 and No. Hei 11-313007, and the contentsof which are incorporated herein by reference.

[0003] 2. Description of the Related Art

[0004]FIG. 28 shows an example of the structure of a furnace wall whichis used in a plant or the like. This wall portion is a combination of aplurality of steel pipes 1 provided upright in parallel to one anotherwith small distances therebetween and fins 2 provided between theindividual steel pipes 1.

[0005] When damage 3 occurs in one of the steel pipes 1 and mending,such as bonding is required, it is difficult for a worker to access thatportion of the damage 3 which faces towards the inside of the furnacebecause of the small distances between the steel pipes 1. To permitaccess to the damage not only from outside the furnace but also frominside, conventionally, welding was carried out after a scaffold 101 wasset up inside the furnace as shown in FIGS. 29 and 30. Because puttingup the scaffold 101 is time consuming, the mending takes a considerabletime.

[0006] Conventionally, fusion welding in which a base metal 250 is cutinto a V shape and padding is applied between the cut surfaces bywelding has been common in bonding metal materials including iron andsteel. A typical means for detecting a welding defect F at the paddingis a P/S (Pulse Signal) probe type ultrasonic detecting apparatus whichcombines an ultrasonic transmitting element and an ultrasonic receivingelement. As shown in FIG. 32, this ultrasonic detecting apparatusirradiates an ultrasonic wave perpendicular to the welded surface andreceives the ultrasonic wave that returns through the same path, inorder to detect a welding defect. The above fusion welding methodrequires several cutting processes and deforms the welded portion orthermally changes the composition. Securing a reliable welded portionwith this method therefore requires highly skilled work and is costly.

[0007] Recently, there has been interest in the diffusion bonding methodas one solution to the above problem. In this diffusion bonding method,an easily-diffusible thin metal sheet is positioned between the surfacesto be connected, and high temperature and pressure are applied to theportion near the surfaces to be connected in such a way that there islittle plastic deformation, thereby diffusing atoms between the surfacesto be connected to accomplish bonding. Diffusion bonding has theadvantages that it does not require any special skill and showsexcellent performance, does not deform the outline of the connectedsurface and provides a connected surface with a uniform composition (seeJapanese Unexamined Patent Application, First Publication No. 62-97784).

[0008] One metal-liquid phase diffusion bonding method which has beenproposed is an amorphous bonding method which uses an amorphous sheet.This amorphous bonding method will now be discussed briefly withreference to the case where a steel pipe is bonded using an amorphoussheet containing boron which reduces the melting point The amorphoussheet is a thin sheet made by rapid solidification and has a thicknessof about 25 μm.

[0009] First, an amorphous sheet whose composition is similar to that ofa steel pipe (base metal) and which contains boron is inserted betweenthe surfaces to be connected. Then, the amorphous sheet is heated to atemperature equal to or lower than the melting point of the base metaland equal to or higher than the melting point of the amorphous sheet.Consequently, boron in the amorphous sheet is diffused in the parentphase, lowering the melting point of the parent phase and melting theparent phase. When heating is maintained in that condition, furtherdiffusion of boron lowers the concentration of boron. This raises themelting point of the parent phase, so that the parent phase is graduallysolidified, thus achieving bonding.

[0010] This bonding method has several advantages, such as a shorterbonding time, a simpler connecting apparatus structure and a lowerheating temperature as compared with the conventional welding.

[0011] An apparatus which implements this amorphous bonding method willbe described briefly with reference to FIG. 31.

[0012] First, an amorphous sheet 72 is inserted between ends to bejoined at the portion to be connected 34 of a steel pipe 1. Next, theupper and lower steel pipes 1 are held by a clamp (not shown) and areurged in the directions of the arrows so as to push together the portionto be connected 34. A high-frequency heating coil 104 heats the portionto be connected 34 which is under pressure from the clamp. Thehigh-frequency heating coil 104 heats the portion to be connected 34 ata temperature equal to or higher than the melting point of the amorphoussheet 72 and equal to or lower than the melting point of the steel pipe1. The aforementioned amorphous bonding is carried out in this way.

[0013] However, the conventional apparatus does not operate on thepremise of bonding of one of a plurality of steel pipes 1 that arearranged with the small distances therebetween, as mentioned previously.That is, steel pipes can be bonded by this apparatus when sufficientworking space can be provided around the steel pipes 1, whereas if aplurality of steel pipes 1 are arranged with small distancestherebetween, sufficient working space cannot be secured around eachsteel pipe 1, and as a result, a high-frequency heating coil or the likecannot be set around the steel pipe 1.

[0014] As the joined or connected surface is formed perpendicular to thematerial surface according to the diffusion bonding method, anultrasonic wave cannot be irradiated perpendicular to the connectedsurface for detecting a welding defect F in the connected surface formedby the diffusion bonding method. This disables the use of a P/S probetype ultrasonic detecting apparatus which combines an ultrasonictransmitting element and ultrasonic receiving element. One method whichuses the conventional P/S probe type ultrasonic detecting apparatus hasbeen proposed in, for example, Japanese Unexamined Patent Application,First Publication No. 6-63771. According to this method, as shown inFIG. 33, surfaces to be connected are so cut as to have certain anglesand are butted so that an ultrasonic wave can be irradiatedperpendicular to the connected surface. However, this method is notpractical because it is difficult to cut the base metal.

[0015] Ultrasonic inspection of a connected surface formed perpendicularto the surface of the base metal can be carried out by a double-probemethod which has an ultrasonic transmitting element and ultrasonicreceiving element separately installed in two probes as shown in FIG.34. This double-probe method uses an ultrasonic transmitting element andan ultrasonic receiving element separate from each other, reflects anultrasonic wave inside the base metal to irradiate the ultrasonic waveon the connected surface at a predetermined angle, reflects theultrasonic wave, reflected at the connected surface, in the base metalagain and receives it at the receiving element.

[0016] However, the conventional double-probe method has a longpropagation path for the ultrasonic wave in the base metal and usesmultiple reflections which significantly attenuates the ultrasonic wave.What is more, because noise is occurs at every reflection, thesensitivity to detect minute defects is diminished. Those disadvantagesmake the conventional double-probe method impractical.

[0017] Accordingly, it is an object of the present invention to providea connecting clamp, a connecting apparatus and a connecting method,which can allow a clamp section and heating member to be positionedaround a rod member, such as a steel pipe, even if ample working spacecannot be secured around the rod member. It is another object of thisinvention to provide an ultrasonic detecting method for inspecting adiffusion-bonded surface which has undergone simple material processingand which has a significantly improved defect detecting performance, andan apparatus which implements this method. It is a further object ofthis invention to provide an ultrasonic detector which is effective ininspecting a bonding defect at a diffusion-bonded portion of,particularly, a steel pipe.

SUMMARY OF THE INVENTION

[0018] A connecting clamp according to one aspect of this inventioncomprises a heating member which surrounds a portion to be connected ofa rod member and heats the portion to be connected; and a first clampsection and a second clamp section positioned on opposite sides of theportion to be connected and clamping the rod member, whereby the portionto be connected is connected by heating the portion to be connected bythe heating member while applying pressure to the portion to beconnected by the first and second clamp sections, and is characterizedin that the first and second clamp sections and the heating member areso arranged as to be slid around an outer surface of the rod member fromone side of the rod member to the other side thereof. Note that the “rodmember” includes a solid rod as well as a tubular member such as a steelpipe.

[0019] A connecting clamp according to another aspect of this invention,which connects a portion to be connected by heating it by means of aheating member, is characterized in that first and second clamp sectionsare so arranged as to be slid around an outer surface of the rod memberfrom one side of the rod member to the other side thereof, the heatingmember has a heating coil so provided as to surround the rod member, theheating coil having a curved portion curved in one plane in such a wayas to have an inside diameter slightly greater than an outside diameterof the rod member and an opening larger than the outside diameter.

[0020] In this case, it is desirable that each of the first and secondclamp sections and the heating member should have a tubular shape andshould comprise a plurality of components which are separable along theradial direction of the tubular shape. The number of separablecomponents has only to be equal to or greater than two, and theseparable components can have any size. The tubular shape may take anyshape, such as a cylinder or a shape has a rectangular cross section, aslong as it can surround a rod member.

[0021] It is further desirable that the first and second clamp sectionsand the heating member should have holding levers for respectivelyholding the first and second clamp sections and the heating member atthe time of sliding the first and second clamp sections and the heatingmember around the outer surface of the rod member.

[0022] Further, it is desirable that the heating member should befurther provided with a cooling pipe and a shield-gas feeding pipe, andeach of the cooling pipe and the shield-gas feeding pipe should have acurved portion curved in one plane in such a way as to have an insidediameter slightly greater than the outside diameter of the rod memberand an opening larger than the outside diameter.

[0023] The heating member may be constituted by stacking a plurality ofshield-gas feeding pipes, a plurality of cooling pipes and a pluralityof heating coils. In this case, as a plurality of shield-gas feedingpipes, a plurality of cooling pipes and a plurality of heating coils arestacked one on another, and they can be combined adequately inaccordance with the condition of the portion to be connected of the rodmember.

[0024] A connecting apparatus according to a further aspect of thisinvention comprises the above-described connecting clamp; a pressureapplying means for applying pressure to the first and second clampsections so as to urge them towards each other; and a power source forsupplying power to the heating member.

[0025] A connecting method according to a still further aspect of thisinvention comprises a wax-material positioning stage of positioning awax material between connecting ends at a portion to be connected of arod member; a clamp-section attaching stage of positioning a first clampsection and a second clamp section on opposite sides of the portion tobe connected and attaching the first and second clamp sections to therod member; and a heating-member attaching stage of attaching a heatingmember in such a way as to surround the portion to be connected; and aconnecting stage of connecting the portion to be connected by heatingthe portion to be connected by the heating member while applyingpressure to the portion to be connected by the first and second clampsections, the clamp-section attaching stage including a step ofarranging the first and second clamp sections so as to be slid around anouter surface of the rod member from one side of the rod member to theother side thereof, the heating-member attaching stage including a stepof arranging the heating member so as to be slid around the outersurface of the rod member from the one side of the rod member to theother side thereof.

[0026] The above-described connecting method of this invention ischaracterized in that the heating member is provided with a heatingcoil, a cooling pipe and a shield-gas feeding pipe, and each of theheating coil, the cooling pipe and the shield-gas feeding pipe having acurved portion curved in one plane in such a way as to have an insidediameter slightly greater than the outside diameter of the rod memberand an opening larger than the outside diameter, and the heating memberattaching stage includes a stage of moving the heating coil, the coolingpipe and the shield-gas feeding pipe forward in such a way that saidplane is approximately parallel to the upright-standing direction of therod member to thereby guide the curved portions from a front side of therod member toward a rear side thereof, and a stage of rotating saidplane in such a way as to become perpendicular the upright-standingdirection, so that the curved portions surround the portion to beconnected.

[0027] It is desirable that the connecting stage should include a stepof heating the rod member so that a distance between the connecting endsof the portion to be connected is decreased by thermal expansion of therod member. Further, the wax-material positioning stage may include astep of positioning an insert member between the connecting ends andpositioning the wax material between the insert member and each of theconnecting ends.

[0028] According to a still further aspect of this invention, anultrasonic detecting method using a double-probe method in which atransmitting element and a receiving element are separated from eachother, directly irradiates an ultrasonic wave onto a surface to beprobed inside a material at a predetermined angle, receives a reflectedultrasonic wave after being reflected inside the material once andperforms probing while adequately changing the distance between thetransmitting element and the surface to be probed and the distancebetween the transmitting element and the receiving element, whereby aninternal defect present along the inspected surface perpendicular to thesurface of the material can be detached.

[0029] As an apparatus which is used in this method, according to thisinvention, an ultrasonic detecting apparatus has been developed whichcomprises a transmitting element for emitting an ultrasonic wave towardsa surface to be probed inside a sample from a surface of the sample at apredetermined angle; and a receiving element for receiving theultrasonic wave reflected from the surface of the sample, thetransmitting element and the receiving element being separated from eachother on a single pedestal, wherein the transmitting element and thereceiving element are movable on the surface of the sample in adirection perpendicular to the surface to be proved, and the distancebetween the transmitting element and the receiving element isarbitrarily changeable.

[0030] This ultrasonic detecting apparatus can be provided with asupplemental unit for ensuring efficient ultrasonic detection of a pipemember, such as a roller which is attached to the pedestal of theultrasonic detecting apparatus so that the apparatus is movable aroundthe pipe member, or a magnet which causes the ultrasonic detectingapparatus to be always attracted to a steel pipe and prevents theapparatus from coming off the steel pipe, at the time of inspecting thesteel pipe, or an encoder attached to the pedestal so that the movingdistance around the pipe member can be determined. To facilitateinspection of the outer surface of a pipe, the signal line of the probeand the signal line of the encoder may be made of a shape memory alloywhich memorizes the same curvature as the pipe's diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 is a perspective view of a first embodiment of thisinvention, illustrating a connecting apparatus attached to a steel pipe;

[0032]FIG. 2 is a front view of a connecting clamp according to a secondembodiment of this invention;

[0033]FIG. 3 is a plan view showing the details of a peripheral portionof an upper clamp section shown in FIG. 2;

[0034]FIG. 4 is a plan view showing a heating coil in FIG. 2;

[0035]FIG. 5 is a side view showing the heating coil in FIG. 4;

[0036]FIG. 6A is a plan view illustrating how to attach the heating coilwhich can slide;

[0037]FIG. 6B is a plan view illustrating how to attach the heating coilwhich is set at a specific position;

[0038]FIG. 6C is a plan view illustrating how to attach the heating coilwhich is secured at a specific position;

[0039]FIG. 7 is a front view depicting a connecting clamp according to athird embodiment of this invention;

[0040]FIG. 8 is a cross-sectional view showing the connecting clamp inFIG. 7 cut in the axial direction;

[0041]FIG. 9 is a plan view showing a heating coil in FIG. 7;

[0042]FIG. 10 is a plan view showing a U-shaped pipe which constitutes acooling pipe in FIG. 7;

[0043]FIG. 11 is a plan view showing a bracket-shaped pipe whichconstitutes the cooling pipe in FIG. 7;

[0044]FIG. 12 is a partly cross-sectional, plan view depicting showing ashield-gas feeding pipe in FIG. 7;

[0045]FIG. 13 is a plan view showing the pipes in FIGS. 10 and 11combined;

[0046]FIG. 14A is a plan view illustrating how to attach the U-shapedpipe in FIG. 10 to a steel pipe with its curved portion inserted betweensteel pipes;

[0047]FIG. 14B is a plan view illustrating how to attach the U-shapedpipe in FIG. 10 to a steel pipe with its curved portion turned;

[0048]FIG. 14C is a plan view illustrating how to attach the U-shapedpipe in FIG. 10 to a steel pipe with its curved portion pulled back;

[0049]FIG. 15A is a plan view showing how to attach the shield-gasfeeding pipe in FIG. 12 to a steel pipe with its curved portionpositioned by the steel pipe;

[0050]FIG. 15B is a plan view showing how to attach the shield-gasfeeding pipe in FIG. 12 to a steel pipe with its curved portionpositioned around the steel pipe;

[0051]FIG. 16A is a front view illustrating a connecting methodaccording to this invention and showing a connecting clamp positioned atan upper portion to be connected;

[0052]FIG. 16B is a front view illustrating the connecting methodaccording to this invention and showing the upper portion to beconnected in the connected state;

[0053]FIG. 16C is a front view illustrating the connecting methodaccording to this invention and showing a gap produced in a lowerportion to be connected;

[0054]FIG. 16D is a front view illustrating the connecting methodaccording to this invention and showing the connecting clamp positionedat the lower portion to be connected;

[0055]FIG. 16E is a front view illustrating the connecting methodaccording to this invention and showing that the connecting work hasbeen completed;

[0056]FIG. 17 is a front view showing an insert ring positioned betweenthe ends to be connected;

[0057]FIG. 18 is a diagram for explaining an inspection method accordingto this invention;

[0058]FIG. 19 is a diagram for explaining an example of the inspectionmethod according to this invention;

[0059]FIG. 20 is a diagram showing the outline of a test for inspectingthe measurement precision;

[0060]FIG. 21 is a diagram showing the relationship between the size ofa defect and the height of an echo;

[0061]FIG. 22A is a diagram exemplifying an echo according to thisinvention;

[0062]FIG. 22B is a diagram exemplifying an echo according to thisinvention;

[0063]FIG. 23 is a plan view showing one example of an ultrasonicdetecting apparatus according to this invention;

[0064]FIG. 24 is a front view of the apparatus shown in FIG. 23;

[0065]FIG. 25 is a side view of the apparatus shown in FIG. 23;

[0066]FIG. 26 is a plan view showing another example of the ultrasonicdetecting apparatus according to this invention;

[0067]FIG. 27 is a side view of the apparatus shown in FIG. 26;

[0068]FIG. 28 is a perspective view showing a part of the wall of afurnace;

[0069]FIG. 29 is a schematic diagram showing a scaffold set up in thefurnace;

[0070]FIG. 30 is a schematic diagram illustrating welding of a steelpipe performed from inside and outside the furnace;

[0071]FIG. 31 is a front view schematically showing the conventionalamorphous bonding method;

[0072]FIG. 32 is a diagram illustrating an inspection method for theconventional fusion bonding;

[0073]FIG. 33 is a diagram illustrating an inspection method for animproved diffusion-bonded surface; and

[0074]FIG. 34 is a diagram illustrating the conventional inspectionmethod adapted to a diffusion-bonded surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

[0075]FIG. 1 is a perspective view illustrating a connecting apparatusaccording to the first embodiment of this invention.

[0076] Reference numeral “1” denotes a steel pipe (rod member) andreference numeral “2” denotes a fin which connects the individual steelpipes 1. Referring to the diagram, a part of the fin 2 on either side ofthe center steel pipe 1 is removed by a predetermined method so that aheating member to be discussed later or the like can be attached to aportion to be connected which requires mending. A connecting clamp 4 isattached to the steel pipe 1 at the portion where the fins 2 have beenremoved. The connecting clamp 4 has an upper clamp section (first clampsection) 6, a lower clamp section (second clamp section) 7 and a heatingmember 9 provided between the upper and lower clamp sections 6 and 7.Attached to the heating member 9 is a connecting head portion 10 whichis provided with a thermometer 11 for measuring the temperature near theportion to be connected.

[0077] The upper clamp section 6 and the lower clamp section 7 arepressed towards each other by a hydraulic system (pressure applyingunit), not shown.

[0078] Though not shown, the heating member 9 accommodates ahigh-frequency heating coil for heating the portion to be connected withfrequency, a cooling pipe for cooling this heating coil and a shield-gasfeeding pipe for feeding a shield gas, such as argon gas, to preventoxidation of the portion to be connected. The heating coil is suppliedwith power from a high-frequency power source 13 via a matchingtransformer 12 for impedance matching.

[0079] A water cooling unit 15 which cools the matching transformer 12is provided on one side of the high-frequency power source 13. Placed onthe top of the high-frequency power source 13 is a controller 17 whichcontrols the supply power or the like based on the output value of thethermometer 11.

[0080] As apparent from FIG. 1, the upper clamp section 6, the lowerclamp section 7 and the heating member 9 in the above-describedstructure are separable along the radial direction at a positionindicated by a reference symbol “A”; they are separated into twocomponents in this embodiment.

[0081] The following will discuss how to connect the steel pipe 1 usingthe above-described apparatus.

[0082] First, the upper clamp section 6 and the lower clamp section 7are positioned on the opposite sides of a portion to be connected (notshown) of the steel pipe 1 and are secured to the steel pipe 1. In thiscase, as the upper and lower clamp sections 6 and 7 are separated intocomponents, the components are slid around the target steel pipe 1 fromthe front side (one side) of the steel pipe 1 to the rear side (theother side) through a small distance between the steel pipe 1 and anadjoining steel pipe 1. Though not shown, a boron-containing amorphoussheet (wax material) having a thickness of about 25 μm is insertedbetween the ends to be joined of the portion to be connected of thesteel pipe 1.

[0083] Next, the heating member 9 is attached between the upper clampsection 6 and the lower clamp section 7 in such a way as to surround theportion to be connected. As the heating member 9 is also separated intocomponents, the components are slid around the target steel pipe 1 fromthe front side of the steel pipe 1 to the rear side through the smalldistance between the steel pipe 1 and the adjoining steel pipe 1. Thestructures of the separated components and method of attaching thecomponents will be described in more detail later under the secondembodiment. Then, the connecting head portion 10 is attached to theheating member 9 so that power can be supplied to the heating member 9from the high-frequency power source 13.

[0084] Thereafter, the upper and lower clamp sections 6 and 7 aredisplaced in the direction so as to narrow the gap between the clampsections 6 and 7 by the hydraulic system, thus pushing together theportion to be connected of the steel pipe 1. When power is supplied tothe high-frequency heating coil of the heating member 9 from thehigh-frequency power source 13 under this situation, the portion to beconnected is heated with the high-frequency. At this time, the supplypower is adjusted by the controller 17 while monitoring the temperaturenear the portion to be connected by means of the thermometer 11.

[0085] As a result, the amorphous sheet is heated to or above themelting point and melted, thereby accomplishing amorphous bonding.

Second Embodiment

[0086] The second embodiment of this invention will now be explainedwith reference to FIGS. 2 to 6.

[0087]FIG. 2 is a front view of the connecting clamp 4 according to thesecond embodiment. It is to be noted that like or the same referencenumerals are given to those components which are common to theindividual embodiments throughout the following description.

[0088]FIG. 2 shows the upper clamp section 6, the lower clamp section 7and the heating member 9 attached to the steel pipe 1. The upper clampsection 6 is secured to an upper-clamp block 20 (see FIG. 3), which iscoupled to a lower block 24 by means of arm portions 22 and 22respectively provided on the right and left sides of the block 20. Twoshaft members 25 and 25 are provided between the upper-clamp block 20and the lower block 24 on the right and left sides to the steel pipe 1.Those shaft members 25 and 25 are movably inserted in a lower-clampblock 27 which is fixed to the lower clamp section 7 (see FIG. 2). Thatis, the lower-clamp block 27 and the lower clamp section 7 are movablerelative to the shaft members 25 and 25.

[0089] As shown in FIG. 3, the upper clamp section 6 comprises a backcomponent 6 a and a front component 6 b. The back component 6 a has anapproximately half-cylindrical shape. The back component 6 a is securedto the upper-clamp block 20 by bolts 28. That is, fastening the bolts 28causes the back component 6 a and the upper-clamp block 20 to sandwichthe steel pipe 1.

[0090] The front component 6 b is fixed to the upper-clamp block 20 andpressed against the steel pipe 1 by bolts 29. The inner surface of thefront component 6 b has a shape which matches the outer surface of thesteel pipe 1. The back component 6 a and front component 6 b hold thesteel pipe 1.

[0091] A holding lever 30 is rotatably attached to the upper end portionof the back component 6 a, so that a worker can hold the back component6 a by holding the grip 30 a of this holding lever 30.

[0092] The structures of the lower clamp section 7 and the lower-clampblock 27 are basically the same as those of the upper clamp section 6and the upper-clamp block 20, except in that a hydraulic screw cylinder32 is fixed to the lower-clamp block 27. This hydraulic screw cylinder32 is also fixed to the lower block 24. The hydraulic screw cylinder 32pushes the lower-clamp block 27 and the lower clamp section 7 in thedirection away from the lower block 24 (upwards in the diagram). Whenthe lower-clamp block 27 and the lower clamp section 7 are pushed inthis way, the lower block 24 is coupled to the upper clamp section 6 viathe arm portions 22 and the upper-clamp block 20, so that the upperclamp section 6 and the lower clamp section 7 are urged towards eachother. That is, pressure is applied to the portion to be connected 34,of the steel pipe 1 held between the upper and lower clamp sections 6and 7.

[0093] With reference to FIGS. 4 and 5, a description will now be givenof the heating member 9 which is so arranged as to surround the portionto be connected 34.

[0094]FIG. 4 is a plan view showing the heating member 9 and an L-shapedarm 37 coupled to this heating member 9. In this diagram, the heatingmember 9 is so arranged as to surround the steel pipe 1. The heatingmember 9 comprises a back component 9 a and a front component 9 b. Theback component 9 a and the front component 9 b are secured to each otherby bolts 38 as shown in FIG. 5. A holding lever 30 is rotatably attachedto the upper end portion of the back component 9 a, so that a worker canhold the back component 9 a by holding a grip 30 a of this holding lever30.

[0095] Provided inside the heating member 9 are a cooling pipe 41 forfeeding a coolant, a shield-gas feeding pipe 41 for feeding a shieldgas, such as argon gas, to prevent oxidation of the portion to beconnected, and a high-frequency heating coil (not shown).

[0096]FIGS. 4 and 5 show exposed portions of the cooling pipe 40 and theshield-gas feeding pipe 41. More specifically, as shown in FIG. 5, thecooling pipe 40 comprises a lower-right cooling pipe 40 a for coolingthe lower right portion of the heating member 9 in the diagram, anupper-right cooling pipe 40 b for cooling the upper right portion of theheating member 9, a lower-left cooling pipe 40 c for cooling the lowerleft portion of the heating member 9 and an upper-left cooling pipe 40 dfor cooling the upper left portion of the heating member 9. Theshield-gas feeding pipe 41 likewise comprises a lower-right shield-gasfeeding pipe 41 a for blowing the shield gas to the lower right portionof the heating member 9, an upper-right shield-gas feeding pipe 41 b forblowing the shield gas to the upper right portion of the heating member9, a lower-left shield-gas feeding pipe 41 c for blowing the shield gasto the lower left portion of the heating member 9, and an upper-leftshield-gas feeding pipe 41 d for blowing the shield gas to the upperleft portion of the heating member 9. The arrows in FIG. 5 indicate theflow directions of the coolant and the shield gas.

[0097] The L-shaped arm 37 is made of a conductor and is electricallyconnected to a high-frequency power source 43 at the end opposite to theheating member 9 Therefore, power is supplied to the high-frequencyheating coil via this L-shaped arm 37. As the L-shaped arm 37 is fixedto the high-frequency power source 43, it cantilevers the heating member9.

[0098] Referring now to FIGS. 6A to 6C, a description will be given ofhow to attach the heating member 9 to the steel pipe 1.

[0099] First, a worker holds the heating member 9 by holding the grip 30a of the holding lever 30 attached to the back component 9 a. Then, theworker slides the back component 9 a around the steel pipe 1 from thefront side of the steel pipe to the rear side in such a way that theback component 9 a passes between the steel pipe 1 and the adjoiningsteel pipe 1 (FIG. 6A).

[0100] The worker further slides the back component 9 a to the positionwhere the back component 9 a is to be secured (FIG. 6B).

[0101] Then, the worker sets the front component 9 b from the front sideof the steel pipe 1 to mate with the back component 9 a and secures thetwo together by the bolts 38 (FIG. 6C).

[0102] Designing the heating member 9 to be separate components 9 a and9 b can allow the heating member 9 to pass between the steel pipes 1. Inother words, even if the space between the target steel pipe 1 and theadjoining steel pipe 1 is limited, the components of the heating member9 can be slid through the space if the radial thicknesses of thecomponents are smaller than the space.

[0103] As the holding lever 30 is rotatably attached to the backcomponent 9 a, a worker remaining in front of the steel pipe 1 can setthe back component 9 a at the rear side of the steel pipe 1 from thefront side. That is, the worker does not need to go around to the rearside of the steel pipe 1. Needless to say, the above-described attachingscheme is likewise applied to the upper and lower clamp sections 6 and7.

Third Embodiment

[0104] The third embodiment of this invention will now be discussed withreference to FIGS. 7 to 14.

[0105]FIG. 7 is a front view depicting the connecting clamp 4 accordingto the third embodiment. As the structures of the upper clamp section 6,the lower clamp section 7, the arm portions 22 and the hydraulic screwcylinder 32 of this connecting clamp 4 differ from those of theconnecting clamp 4 that has been explained with reference to FIG. 2 onlyin that the connecting clamp 4 of the third embodiment is upside sidedown with respect to the connecting clamp 4 of the second embodiment,their descriptions will not be repeated. That is, the scheme ofattaching the upper and lower clamp sections 6 and 7 in the thirdembodiment is the same as that in the second embodiment.

[0106] As apparent from FIGS. 7 and 8, the heating member 9 of thisembodiment comprises a lamination of a plurality of high-frequencyheating coils 45, a plurality of cooling pipes 46 and a plurality ofshield-gas feeding pipes 47. The cooling pipes 46 are positioned on andbelow the stack of the heating coils 45, and the shield-gas feedingpipes 47 are positioned on and the below the cooling pipes 46. Aplurality of spacers 49 for electric insulation are positioned betweenthe heating coils 45 and the cooling pipes 46.

[0107] As shown in FIG. 9, each heating coil 45 comprises a U-shapedpipe of copper which has a curved portion 45 a and in which coolingwater can flow. The curved portion 45 a is curved within one plane insuch a way as to have an inside diameter slightly larger than theoutside diameter of the steel pipe 1 and have an opening 45 b largerthan that outside diameter. The curved portion 45 a is arranged at theback of the steel pipe 1 and a copper plate 51 is positioned in front ofthe steel pipe 1. As apparent from FIG. 9, this copper plate 51 isseparated into right and left portions, which are electrically connectedto respective right and left linear portions 45 c of the heating coil45. The curved portion 45 a and copper plate 51 completely surround thesteel pipe 1.

[0108] Each cooling pipe 46 comprises a U-shaped pipe 53 (see FIG. 10)and a bracket-shaped pipe 54 (see FIG. 11). The U-shaped pipe 53 has acurved portion 53 a which is curved within one plane in such a way as tohave an inside diameter slightly larger than the outside diameter of thesteel pipe 1 and have an opening 53 b larger than that outside diameter.

[0109] The bracket-shaped pipe 54 comprises a first pipe 55 and a secondpipe 56, which extend in the horizontal direction in FIG. 11, and ajoint pipe 57 which connects the first and second pipes 55 and 56 andextends in the vertical direction in FIG. 11. Plate members 58 and 58are obliquely attached to the right-hand ends of the first and secondpipes 55 and 56, to prevent the coolant that flows inside the pipes fromflowing out. The obliquely attached plate members 58 and the joint pipe57 form an outline which matches the outer surface of the of the steelpipe 1 (see FIG. 13 to be discussed later).

[0110] The width, W2, between the outer side of the first pipe 55 of thebracket-shaped pipe 54 and the outer side of the second pipe 56 issmaller than the width, W1, of the opening 53 b of the U-shaped pipe 53.As shown in FIG. 13, therefore, the U-shaped pipe 53 and thebracket-shaped pipe 54 can be combined in such a manner that thebracket-shaped pipe 54 is put inside the U-shaped pipe 53. With thepipes 53 and 54 combined this way, the curved portion 53 a of theU-shaped pipe 53 and the plate members 58 and the joint pipe 57 of thebracket-shaped pipe 54 entirely surround the steel pipe 1.

[0111] Each shield-gas feeding pipe 47 comprises two pipes of the sameshape combined symmetrically, as shown in FIG. 12. Each of the two pipeshas a curved portion 60 which is curved within one plane in such a wayas to have an inside diameter slightly larger than the outside diameterof the steel pipe 1 and have an opening 61 larger than that outsidediameter. Plate members 62 are respectively attached to both ends ofeach curved portion 60 to prevent the shield gas that flows inside eachpipe from flowing out. The shield gas is blown out through a pluralityof holes 64 formed in the inner wall of the curved portion 60.

[0112] Referring now to FIGS. 14A to 14C, a description will be given ofhow to arrange the U-shaped pipe 53, which constitutes the cooling pipe46 shown in FIG. 10, around the steel pipe 1.

[0113] First, the plane of the curved portion 53 a of the U-shaped pipe53 is set approximately parallel to the upright-standing direction ofthe steel pipe 1, and the U-shaped pipe 53 is moved forward (see FIG.14A). This allows the curved portion 53 a to be put through between thesteel pipes 1 and guided toward the back of the steel pipe 1 from thefront side thereof.

[0114] Next, the plane is rotated approximately 90° so as to intersectthe upright-standing direction of the steel pipe 1 (see FIG. 14B).

[0115] Then, the U-shaped pipe 53 is pulled back towards the operator sothat the curved portion 53 a surrounds the steel pipe 1 (see FIG. 14C).

[0116] Repeating the above steps allows a plurality of U-shaped pipes tobe positioned one on another around the steel pipe 1.

[0117] As the curved portion 53 a of the U-shaped pipe 53 is formed inone plane, the curved portion 53 a can be put through the space betweenthe adjoining steel pipes 1, even if there is limited space around thetarget steel pipe 1, by letting this plane pass by the steel pipe 1 inparallel to the upright-standing direction of the steel pipe 1. That is,the curved portion 53 a can be put through the space if the space iseven only slightly larger than the diameter of the U-shaped pipe 53.

[0118] Further, because the curved portion 53 a has an opening 53 blarger than the outside diameter of the steel pipe 1, the inner surfaceof the curved portion 53 a can be set close to the steel pipe 1 via theopening 53 b so that the curved portion 53 a surrounds the steel pipe 1.

[0119] Although the U-shaped pipe 53 which constitutes the cooling pipe46 has been explained above with reference to FIGS. 14A to 14C, eachheating coil 45 likewise comprises a U-shaped pipe so that, like theU-shaped pipes 53, the U-shaped pipes of the heating coils 45 can beassembled so as to surround the steel pipe 1.

[0120] Referring now to FIGS. 15A and 15B, a description will be givenof how to arrange the shield-gas feeding pipe 47, shown in FIG. 22,around the steel pipe 1.

[0121] First, the plane including the curved portion 60 of one of thetwo pipes of the shield-gas feeding pipe 47 is set approximatelyparallel to the upright-standing direction of the steel pipe 1, and onepipe part of the shield-gas feeding pipe 47 is moved forward (see FIG.15A). As a result, the curved portion 60 is moved forward to the spacebetween the target steel pipe 1 and the adjoining steel pipe 1.

[0122] Next, the plane is rotated approximately 90° so as to intersectthe upright-standing direction of the steel pipe 1 (see FIG. 15B). Thiscauses the inner surface side of the curved portion 60 to come close tothe outer surface of the steel pipe 1.

[0123] As the above operations are carried out for both sides of thesteel pipe 1, the shield-gas feeding pipe 47 is so positioned as toentirely surround the steel pipe 1. Repeating all the operations canallow the shield-gas feeding pipes 47 to be positioned one on anothervertically.

[0124] As each curved portion 60 of each shield-gas feeding pipe 47 hasthe form of one half of a circular pipe which has been segmented intotwo in the insertion direction (see FIG. 12), positioning the shield-gasfeeding pipe 47 around the steel pipe 1 does not require the steps ofpositioning the curved portion past the space between the adjoiningsteel pipes 1 and then pulling it back, which are needed for theU-shaped pipe. The shield-gas feeding pipe 47 can be so set that thecurved portions 60 surround the steel pipe 1 by simply inserting eachpipe of the shield-gas feeding pipe 47 between the steel pipes 1 andturning the pipe by about 90° when the curved portion 60 is positionedby the target steel pipe 1.

Fourth Embodiment

[0125] Referring now to FIGS. 16A to 16E, a description will be given ofanother connecting method which uses the connecting clamp of thisinvention as the fourth embodiment.

[0126] First, a portion around the portion to be mended of the steelpipe 1 is removed and the fins 2 on both sides of the steel pipe 1 areremoved so that the connecting clamp 4 can be attached to the steel pipe1. Next, a new pipe 66 which is slightly shorter than the removedportion of the steel pipe 1 is attached to the steel pipe 1, and thenthe connecting clamp 4 is attached to an upper portion to be connected34 a on which an amorphous sheet (not shown) is provided (see FIG. 16A).

[0127] Then, the upper portion to be connected 34 a is heated by theheating coil while pressure is applied to the upper portion to beconnected 34 a by the upper and lower clamp sections (see FIG. 16B).

[0128] In this state, a predetermined gap (distance) G is formed betweenthe ends to be joined of a lower portion to be connected 34 b (see FIG.16C).

[0129] Further, a heater 68 is attached to the new pipe 66 and theconnecting clamp is attached to the lower portion to be connected 34 bon which an amorphous sheet is provided. Then, the new pipe 66 is heatedby the heater 68 so that the new pipe 66 thermally expands, thusreducing the gap G formed the lower portion to be connected 34 b. Underthis situation, amorphous bonding using the connecting clamp 4 isperformed (see FIG. 16D).

[0130] Next, the heater 68 and the connecting clamp 4 are removed, whichcompletes the mending of the steel pipe 1 (FIG. 16E).

[0131] Note that like the heating member 9, the heater 68 may bedesigned to be separable and provided with a holding lever as shown inFIGS. 6A to 6C showing the second embodiment, so that the heater 68 canbe slid around the new pipe 66 at the time of attachment. Alternatively,like the heating coil 45, the heater 68 may be comprised of a U-shapedpipe as shown in FIG. 9, which shows the third embodiment.

[0132] When the gap G formed the lower portion to be connected 34 b islarge as shown in FIG. 16C, the scheme illustrated in FIG. 17 can beemployed.

[0133]FIG. 17 is a schematic diagram showing the portion to be connected34 of the steel pipe 1 surrounded by the heating coil 45. An insert ring(insert member) 70 and amorphous sheets 72 and 72 provided on theopposite sides of the insert ring 70 are positioned between the ends tobe joined of the portion to be connected 34. The axial directionallength of the insert ring 70 is so set as to cover the gap G and isparticularly set shorter than the axial directional length of theheating coil 45. The cross-sectional shape and the material of theinsert ring 70 are the same as those of the steel pipe 1.

[0134] When an insert ring 70 is sufficiently long to cover the gap G,as shown in FIG. 17, it is unnecessary to cause thermal expansion usingthe heater 68 as shown in FIG. 16D or it is unnecessary to strongly heatthe steel pipe even if the heater 68 is used.

[0135] A description will now be given of a method and apparatus forinspecting for defects in a surface bonded by the above-describeddiffusion bonding method.

[0136]FIG. 18 is a diagram for explaining the principle of ultrasonicdetection using the method of this invention.

[0137] In FIG. 18, it is assumed that the material 250 to be inspectedhas a thickness T and has undergone diffusion bonding so that it has abonded surface J-J at right angles to the surface, 250 a of the material250 to be inspected at a point R and a defect which is produced in thebonded surface J-J from the surface 250 a is to be inspected.

[0138] It is assumed that in the situation shown in FIG. 18, a defect Fis detected when the ultrasonic emitting point P of a transmitting probe203 is separated from the intersection R of the surface 250 a and thebonded surface J-J by a distance Y₁ and the reflected ultrasonic wave isreceived by receiving probe 204 at point S which is separated from thepoint P by a distance L. In this case, the emitted ultrasonic wavedirectly hits the surface to be probed at an angle of θ with respect tothe bonded surface J-J, is reflected at a point F, is further reflectedonce at a point Q on the other surface (bottom surface) 250 b of thematerial to be inspected 250, and then reaches the receiving probe 204.According to this invention, it is important that the ultrasonic wavethat is transmitted inside the material to be inspected 250 should hitthe surface to be probed directly in order to preventreflection-originated attenuation of the ultrasonic wave to the greatestextent possible.

[0139] Given that in FIG. 18, the symbol used are:

[0140] T: plate thickness,

[0141] d: depth to the defect from the surface of the material to beinspected,

[0142] L: distance between the transmitting probe and the receivingprobe,

[0143] θ: incident angle of the ultrasonic wave,

[0144] Y₁: distance between the bonded surface and the transmittingprobe,

[0145] Y₂: distance between the bonded surface and the point ofreflection inside the material to be inspected,

[0146] Y₃: distance between the point of reflection inside theto-be-inspected material and the surface of the receiving probe, and

[0147] Y₄: distance between the bonded surface and the surface of thereceiving probe, then the following equations apply:

Y ₁ =d·tan θ,

Y ₂=(T−d)·tan θ,

Y ₃ =T−·tan θ, and

Y ₄ =Y ₂ +Y ₃.

[0148] From the above equations, the distance L between the transmittingprobe and the receiving probe and the depth d to the defect from thesurface of the material to be inspected satisfy the followingrelationship.

L=Y ₄ −Y ₁

=Y₂+Y₃—Y₁

=(T−d)·tan θ+T·tan θ−d·tan θ

=2·(T−d)·tan θ  (1)

[0149] Further, the distance L between the transmitting probe and thereceiving probe and the distance Y₁ between the bonded surface and thetransmitting probe satisfy the following relationship.

L=2·(T·tan θ−Y ₁)  (2)

[0150] An echo when the transmitting probe 203 is moved from the bondedsurface J-J by a distance Y₁ can be detected at the position where thedistance between the transmitting probe 203 and the receiving probe 204is L, and the relationship between L and Y₁ satisfies the equation 2.

[0151] As the transmitting probe 203 is moved sequentially from thepoint R on the bonded surface, inner defects present in thethicknesswise direction of the material to be inspected 250 along thebonded surface J-J can be detected sequentially. This is illustrated inFIG. 19, which shows an inner defect F₁ at a depth d₁ and an innerdefect F₂ at a depth d₂. The distance L between the transmitting probe203 and the receiving probe 204 is L₁ in the case of detecting the innerdefect F₁ and is L₂ in the case of detecting the inner defect F₂. Thedistance Y₁(=t₁) between the bonded surface and the transmitting probe203 and the distance L between the transmitting probe 203 and thereceiving probe 204 satisfies the relationship given by the equation 2.

[0152] As shown in FIG. 19, the distance between the bonded surface J-Jand the transmitting probe 203 in the case of detecting the inner defectF₁ is t₁ and the distance between the bonded surface J-J and thetransmitting probe 203 in the case of detecting the inner defect F₂ ist₂. As the transmitting probe 203 and the receiving probe 204 are movedsequentially, it is possible to detect the depth from the surface of aninner defect. It is understood from FIG. 19 that the deeper an innerdefect is from the surface, the shorter the distance L between thetransmitting probe 203 and the receiving probe 204. While this methodcan inspect nearly the entire area of the bonded surface, the minimumvalue of the distance L between the transmitting probe 203 and thereceiving probe 204 is determined by the sizes of the transmitting probe203 and the receiving probe 204 and cannot be made substantially zero.This limits the depth at which defects can be detected so that there isan undetectable area at the deepest part of the sample.

[0153] When there is one reflection of an ultrasonic wave at the surfaceof the material as shown in FIGS. 18 and 19, an echo appears clearly,thus ensuring excellent detection of minute defects. It is thereforeimportant to receive ultrasonic waves which has been reflected onlyonce. When the position of inspection becomes too deep to secure thedistance between the probes, it is inevitable that the ultrasonic wavewill be further reflected twice so that the echo which has beenreflected three times is to be caught. This is feasible, although thesensitivity is reduced.

[0154]FIG. 21 shows the results of an experiment for inspecting thedetection precision according to the method of this invention. As shownin FIG. 20, a sample can have holes of 0.5 mm to 3.0 mm in diameter,formed horizontally with a length of 10 mm at a depth of 4 mm from thesurface of a steel pipe of 6 mm in thickness. An ultrasonic wave isirradiated onto this sample at an angle of 45 degrees, reflected once atthe bottom of the steel pipe and the resultant echo is detected. Asshown in FIG. 21 which shows the heights of echoes detected this way, itis apparent that this invention can clearly detect even a defect with adiameter of 0.5 mm and is significantly effective in inspecting defectsin a diffusion-bonded surface.

[0155]FIGS. 22A and 22B show examples of the behavior of echoes obtainedin the aforementioned experiment and shown on a display. In the diagram,It is a pulse echo and Iw is a shape echo from the end face of ato-be-inspected material and neither is relevant to detection of adefect. F is an echo originated from an inner defect. FIG. 22A shows thecase where there is no defect and echoes other than the pulse echo andthe shape echo show the noise level. FIG. 22b shows the case where thereis a defect, and clearly shows a defect echo F. According to the methodof this invention, an ultrasonic wave is irradiated directly onto thesurface to be probed and the number of reflections at the surfaces ofthe material to be inspected is suppressed as much as possible, so thatthe propagation length of the ultrasonic wave is minimized. As a result,the method of this invention reduces the attenuation of the ultrasonicwave and the chances of picking up noise, thus making the echoes clearerand making it possible to detect minute inner defects.

[0156] As another embodiment of this invention, a method which reflectsan ultrasonic wave incident to a material to be inspected at apredetermined angle once off a surface of the material to be inspectedand directly picks up the ultrasonic wave that is reflected at thesurface to be probed will be discussed below. In this method, thepositions of the transmitting probe 203 and the receiving probe 204 inFIG. 18 are reversed, and the propagation passage of the ultrasonic waveis reversed. While the ultrasonic wave that hits the surface to beprobed becomes slightly weaker, the length of the entire propagationpassage is the same, and as a result, this method does not raise anypractical problems. In this case, the relationship of the equation 2 canbe applied as it is except that Y₁, should be read as the distancebetween the bonded surface and the transmitting probe 203.

[0157] An apparatus which uses the method of this invention will bediscussed below.

[0158] FIGS. 23 to 25 are diagrams showing one embodiment of anapparatus which uses the method of this invention. FIG. 23 is a planview, FIG. 24 is a front view, and FIG. 25 is a side view. Thisembodiment is an example of an apparatus which probes a member acquiredby diffusion-bonding a flat plate. The diffusion-bonded surface isformed perpendicular to the surface of the flat plate. In thisapparatus, as shown in FIG. 23, both ends of two pedestals 201 are fixedto frames 202 a and 202 b, thus completing the entire frame. Placedbetween the opposing two pedestals 201 are the transmitting probe 203 inwhich a transmitting element 205 is installed and the receiving probe204 in which a receiving element 206 is installed. Attached to the sidesof each of the transmitting probe 203 and the receiving probe 204 arearms 210 which are fitted in grooves 211 formed in the pedestals 201 insuch a way as to be slidable in the X-X direction along the pedestals201. One of the pedestals 201 is provided with a reference line 207 foralignment of the surface to be probed and a scale 222 for computing thedistance by which each probe is moved. The distances by which the probesare moved are determined by using markers 208 and 209 which indicate theultrasonic-wave transmitting and receiving positions of the probes.

[0159] The bottom of this apparatus is finished to have a smooth surfaceso that the bottoms of the pedestals 201 are in the same plane as thebottoms of the transmitting probe 203 and the receiving probe 204 andare closely in contact with the surface of the material to be inspected250 as shown in FIGS. 24 and 25.

[0160] At the time of probing the material to be inspected 250, thereference line 207 of this apparatus is aligned with the surface to beprobed J-J so that the center axis X-X of this apparatus isperpendicular to the surface to be probed J-J first. Then, after themarker 208 of the transmitting probe 203 is aligned with the referenceline 207, the transmitting probe 203 is moved gradually away from thesurface to be probed J-J and the receiving probe 204 is moved in such away as to maintain the relationship L=2×(T·tan θ−Y₁) according to theequation 2. Probing is carried out this way. At this time, given thatthe incident angle θ of the ultrasonic wave is 45 degrees, the equation2 becomes L=2×(T−Y ₁).

[0161] As the apparatus of this invention can be moved freely on aplane, it can detect an inner defect in the diffusion-bonded surface ofthe plate material with a high precision. For a plate member with asimple surface shape, a single apparatus can be used in various ways.

[0162] Next, another example of the apparatus of this invention, whichinspects an inner defect in a pipe member, will be discussed below.

[0163] The principle of measurement is the same as that of theabove-described case of a plate member. It is to be noted, however, thatfor a pipe member, the bottom of the pedestal and the bottom of theprobe should match the curvature of the outside surface of the pipemember and the surface of the pipe member and the bottom of thisapparatus should closely contact each other. For pipe members withdifferent outside diameters, an apparatus for detecting inner defects ina pipe member, whose having inter pedestal and probe have bottoms whichare changeable according to the outside diameters of pipe members,should be prepared. Such preparation makes it basically possible todetect an inner defect in any pipe member. To facilitate probing of asteel pipe, however, support rollers and a magnet can be furtherattached to the pedestal according to this invention so that a force ofattraction always acts on the steel pipe and the apparatus is movable inthe circumferential direction while the apparatus is in close contactwith the steel pipe. As another example, an encoder is attached to thepedestal to measure the distance moved in the circumferential directionso that the circumferential position of an inner defect can be known.Further, the signal line of the probe and the signal line of the encoderare made of a shape memory alloy, thus facilitating inspection of theback surface of a pipe member. Examples of the above will be discussedspecifically referring to FIGS. 26 and 27.

[0164]FIGS. 26 and 27 show an ultrasonic detecting apparatus for a steelpipe according to this invention. FIG. 26 is a plan view and FIG. 27 isa side view. In FIG. 26, the transmitting probe 203 and the receivingprobe 204 are mounted on the center portion of the pedestal 201 on whichsupport rollers 212, an encoder roller 220 and a supplemental unit arefurther mounted. The probe-sliding mechanism in the vicinity of thetransmitting probe 203 and the receiving probe 204 are basically thesame as those of a plate member and their its detailed descriptions willbe omitted.

[0165] For the ultrasonic detecting apparatus for a pipe member, thesurface of each probe should be matched with the curvature of theoutside diameter of a pipe member (steel pipe) 251. In this apparatus,as shown in FIG. 27, the bottoms of the transmitting probe 203 and thereceiving probe 204 are integrated with the bottom of the pedestal 201and are processed to have the same curvature as the outside surface ofthe pipe member 251. Attached to the pedestal 201 are four supportrollers 212 for allowing the entire apparatus to move in thecircumferential direction of the pipe member 251. The pedestal 201 maybe moved in the circumferential direction of the pipe member 251manually or by using a drive unit.

[0166] Further, a magnet 213 is embedded in the pedestal 201 so as toalways pull the apparatus towards the pipe member 251 at the time ofinspection. It is therefore possible to easily detect a defect at theback of a pipe member 251 which may be set upright or positionedhorizontally. The magnet 213 may be a permanent magnet or anelectromagnet. In the case of an electromagnet, the attraction of themagnet 213 can be stopped for separation from the pipe member 251 whenthe current supply is stopped. As the encoder roller 220 is attached tothe pedestal 201, the amount of movement of each probe can be determinedwhen the apparatus is moved in the circumferential direction. Referencenumeral “221” denotes an encoder, which permits the position of an innerdefect in the circumferential direction of the pipe member 251 to bedetected.

[0167] A shape memory alloy is used for signal lines 214 of the probeand encoder in the ultrasonic detecting apparatus of this invention. Theshape memory alloy used is a Ti—Ni based alloy which contains 49 at % ofTi and 51 at % of Ni. This shape memory alloy is subjected in advance toa shape-memory heat treatment so as to memorize a curvature greater thanthe outside diameter of the pipe member 251. The activation temperatureof the shape memory alloy is set to 32 to 38° C. to make it adapt thepredetermined shape when touched by the hand of an operator. The use ofthe shape memory alloy for the signal lines 214 allows the signal lines214, which have arbitrary shapes at the time they are attached to theapparatus, to change their shapes to match the outside diameter of thepipe member 251 when they are touched by an operator's hand when theattachment is completed. This prevents the signal lines 214 from gettingentangled at the back of the pipe member 251 and can therefore ensuresmooth measurement.

[0168] It is possible to supply electric signals, acquired from thosesignal lines 214, to a micro computer system and display the inspectionresults as a plan view or a cross-sectional view on a display or printout images. It is also possible to automate detection scanning or attacha plurality of apparatuses to a single long pipe member 251 so that thelong pipe member 251 can be probed at plural positions simultaneously.

[0169] This apparatus can inspect the entire circumferential directionof a target steel pipe for inner defects, even in the case where, likeboiler tubes, thin steel pipes having outside diameters of about 30 mmare positioned at small intervals of about 10 mm and so therebetween.

What is claimed is:
 1. A connecting clamp comprising: a heating memberwhich surrounds a portion to be connected of a rod member and heats saidportion to be connected; and a first clamp section and a second clampsection positioned on opposite sides of said portion to be connected andclamping said rod member, whereby said portion to be connected isconnected by heating said portion to be connected by said heating memberwhile applying pressure to said portion to be connected by said firstand second clamp sections, said first and second clamp sections and saidheating member being so arranged as to be slid around an outer surfaceof said rod member from one side of said rod member to the other sidethereof.
 2. The connecting clamp according to claim 1, wherein each ofsaid first and second clamp sections and said heating member has atubular shape and comprises a plurality of components separable along anradial direction of said tubular shape.
 3. The connecting clampaccording to claim 1, wherein said first and second clamp sections andsaid heating member have holding levers for respectively holding saidfirst and second clamp sections and said heating member when slidingsaid first and second clamp sections and said heating member around saidouter surface of said rod member.
 4. The connecting clamp according toclaim 2, wherein said first and second clamp sections and said heatingmember have holding levers for respectively holding said first andsecond clamp sections and said heating member when sliding said firstand second clamp sections and said heating member around said outersurface of said rod member.
 5. A connecting clamp comprising: a heatingmember which surrounds a portion to be connected of a rod member andheats said portion to be connected; and a first clamp section and asecond clamp section positioned on opposite sides of said portion to beconnected and clamping said rod member, whereby said portion to beconnected is connected by heating said portion to be connected by saidheating member while apply pressure to said portion to be connected bysaid fist and second clamp sections, said first and second clampsections being so arranged as to be slid around an outer surface of saidrod member from one side of said rod member to the other side thereof,said heating member having a heating coil so provided as to surroundsaid rod member, said heating coil having a curved portion curved in oneplane in such a way as to have an inside diameter slightly greater thanan outside diameter of said rod member and an opening larger than saidoutside diameter.
 6. The connecting clamp according to claim 5, whereineach of said first and second clamp sections has a tubular shape andcomprises a plurality of components which are separable along an radialdirection of said tubular shape.
 7. The connecting clamp according toclaim 5, wherein said first and second clamp sections have holdinglevers for respectively holding said first and second clamp sections ata time of sliding said first and second clamp sections around said outersurface of said rod member.
 8. The connecting clamp according to claim6, wherein said first and second clamp sections have holding levers forrespectively holding said first and second clamp sections at a time ofsliding said first and second clamp sections around said outer surfaceof said rod member.
 9. The connecting clamp according to claim 5,wherein said heating member is further provided with a cooling pipe anda shield-gas feeding pipe; each of said cooling pipe and said shield-gasfeeding pipe having a curved portion curved in one plane in such a wayas to have an inside diameter slightly greater than an outside diameterof said rod member and an opening larger than said outside diameter. 10.The connecting clamp according to claim 6, wherein said heating memberis further provided with a cooling pipe and a shield-gas feeding pipe;each of said cooling pipe and said shield-gas feeding pipe having acurved portion curved in one plane in such a way as to have an insidediameter slightly greater than an outside diameter of said rod memberand an opening larger than said outside diameter.
 11. The connectingclamp according to claim 7, wherein said heating member is furtherprovided with a cooling pipe and a shield-gas feeding pipe; each of saidcooling pipe and said shield-gas feeding pipe having a curved portioncurved in one plane in such a way as to have an inside diameter slightlygreater than an outside diameter of said rod member and an openinglarger than said outside diameter.
 12. The connecting clamp according toclaim 8, wherein said heating member is further provided with a coolingpipe and a shield-gas feeding pipe; each of said cooling pipe and saidshield-gas feeding pipe having a curved portion curved in one plane insuch a way as to have an inside diameter slightly greater than anoutside diameter of said rod member and an opening larger than saidoutside diameter.
 13. The connecting clamp according to claim 9, whereinsaid heating member is constituted by stacking a plurality of shield-gasfeeding pipes, a plurality of cooling pipes and a plurality of heatingcoils.
 14. The connecting clamp according to claim 10, wherein saidheating member is constituted by stacking a plurality of shield-gasfeeding pipes, a plurality of cooling pipes and a plurality of heatingcoils.
 15. The connecting clamp according to claim 11, wherein saidheating member is constituted by stacking a plurality of shield-gasfeeding pipes, a plurality of cooling pipes and a plurality of heatingcoils.
 16. The connecting clamp according to claim 12, wherein saidheating member is constituted by stacking a plurality of shield-gasfeeding pipes, a plurality of cooling pipes and a plurality of heatingcoils.
 17. A connecting apparatus comprising: a connecting clamp asrecited in any one of claims 1 to 4; pressing means for applyingpressure to said first and second clamp sections in such a direction asto come closer to each other; and a power source for supplying power tosaid heating member.
 18. A connecting apparatus comprising: a connectingclamp as recited in any one of claims 5 to 16; pressing means forapplying pressure to said first and second clamp sections in such adirection as to come closer to each other; and a power source forsupplying power to said heating member.
 19. A connecting methodcomprising: a wax-material positioning stage of positioning a waxmaterial between connecting ends at a portion to be connected of a rodmember, a clamp-section attaching stage of positioning a first clampsection and a second clamp section on opposite sides of said portion tobe connected and attaching said first and second clamp sections to saidrod member; and a heating-member attaching stage of attaching a heatingmember in such a way as to surround said portion to be connected; and aconnecting stage of connecting said portion to be connected by heatingsaid portion to be connected by said heating member while apply pressureto said portion to be connected by said first and second clamp sections,said clamp-section attaching stage including a step of arranging saidfirst and second clamp sections so as to be slid around an outer surfaceof said rod member from one side of said rod member to the other sidethereof, said heating-member attaching stage including a step ofarranging said heating member so as to be slid around said outer surfaceof said rod member from said one side of said rod member to said otherside thereof.
 20. A connecting method comprising: a wax-materialpositioning stage of positioning a wax material between connecting endsat a portion to be connected of a rod member; a clamp-section attachingstage of positioning a first clamp section and a second clamp section onopposite sides of said portion to be connected and attaching said firstand second clamp sections to said rod member; and a heating-memberattaching stage of attaching a heating member in such a way as tosurround said portion to be connected; and a connecting stage ofconnecting said portion to be connected by heating said portion to beconnected by said heating member while applying pressure to said portionto be connected by said first and second clamp sections, saidclamp-section attaching stage including a step of arranging said firstand second clamp sections so as to be slid around an outer surface ofsaid rod member from one side of said rod member to the other sidethereof, said heating member being provided with a heating coil, acooling pipe and a shield-gas feeding pipe, each of said heating coil,said cooling pipe and said shield-gas feeding pipe having a curvedportion curved in one plane in such a way as to have an inside diameterslightly greater than an outside diameter of said rod member and anopening larger than said outside diameter, said heating-member attachingstage including a step of moving said heating coil, said cooling pipeand said shield-gas feeding pipe forward in such a way that said oneplane becomes approximately parallel to an upright-standing direction ofsaid rod member to thereby guide said curved portions from a front sideof said rod member toward a rear side thereof, and a stage of rotatingsaid plane in such a way as to become perpendicular to saidupright-standing direction, so that said curved portions surround saidportion to be connected.
 21. The connecting method according to claim19, wherein said connecting stage includes a step of heating said rodmember so that a distance between said connecting ends of said portionto be connected is decreased by thermal expansion of said rod member.22. The connecting method according to claim 20, wherein said connectingstage includes a step of heating said rod member so that a distancebetween said connecting ends of said portion to be connected isdecreased by thermal expansion of said rod member.
 23. The connectingmethod according to any one of claims 19 to 22, wherein said waxmaterial positioning stage includes a step of positioning an insertmember between said connecting ends and positioning said wax materialbetween said insert member and each of said connecting ends.
 24. Anultrasonic detecting method using a double-probe method in which atransmitting element and a receiving element are separated from eachother, for directly irradiating an ultrasonic wave onto a surface to beprobed inside a material at a predetermined angle, receiving a reflectedultrasonic wave after it is reflected inside said material once andperforming probing while adequately changing a distance between saidtransmitting element and said surface to be probed and a distancebetween said transmitting element and said receiving element.
 25. Theultrasonic detecting method according to claim 24, wherein probing iscarried out while maintaining a relationship of L=2·(T·tan θ−Y₁) where Tis a thickness of said material, Y₁ is said distance between saidsurface to be probed and said transmitting element, L is said distancebetween said transmitting element and said receiving element, and θ isan incident angle of said ultrasonic wave.
 26. An ultrasonic detectingmethod using a double-probe method in which a transmitting element and areceiving element are separated from each other, for directlyirradiating an ultrasonic wave inside a material at a predeterminedangle, reflecting said ultrasonic wave at an inner surface of saidmaterial once and then causing said ultrasonic wave to hit a surface tobe probed inside said material, directly receiving a reflectedultrasonic wave, and performing probing while adequately changing adistance between said transmitting element and said surface to be probedand a distance between said transmitting element and said receivingelement.
 27. The ultrasonic detecting method according to claim 24,wherein a surface of said material and said surface to be probed form anangle of 90 degrees.
 28. The ultrasonic detecting method according toclaim 25, wherein a surface of said material and said surface to beprobed form an angle of 90 degrees.
 29. The ultrasonic detecting methodaccording to claim 26, wherein a surface of said material and saidsurface to be probed form an angle of 90 degrees.
 30. The ultrasonicdetecting method according to any one of claims 24 to 29, wherein saidultrasonic wave is irradiated onto the surface of said material at anangle of 45 degrees.
 31. An ultrasonic detecting apparatus comprising: atransmitting element for emitting an ultrasonic wave toward a surface tobe probed inside a sample from a surface of said sample at apredetermined angle; and a receiving element for receiving saidultrasonic wave reflected from said surface of said sample, saidtransmitting element and said receiving element being separated fromeach other on a single pedestal, said transmitting element and saidreceiving element being movable on said surface of said sample in adirection perpendicular to said surface to be probed, a distance betweensaid transmitting element and said receiving element being arbitrarilychangeable.
 32. The ultrasonic detecting apparatus according to claim31, wherein each of a bottom surface of said pedestal, a bottom surfaceof said transmitting element and a bottom surface of said receivingelement has the same radius of curvature as an outside diameter of apipe member which is said sample.
 33. The ultrasonic detecting apparatusaccording to claim 32, further comprising a support roller on saidpedestal so that said ultrasonic detecting apparatus is movable on asurface of said pipe member along a peripheral direction thereof. 34.The ultrasonic detecting apparatus according to claim 32, furthercomprising a magnet on said pedestal so that an attractive force actsbetween said pipe member which is a steel pipe and said detectionapparatus.
 35. The ultrasonic detecting apparatus according to claim 33,further comprising a magnet on said pedestal so that attractive forceacts between said pipe member which is a steel pipe and said detectionapparatus.
 36. The ultrasonic detecting apparatus according to claim 32,further comprising an encoder on said pedestal so that a distance movedalong a peripheral direction of said pipe member can be determined. 37.The ultrasonic detecting apparatus according to claim 33, furthercomprising an encoder on said pedestal so that a distance moved along aperipheral direction of said pipe member can be determined.
 38. Theultrasonic detecting apparatus according to claim 34, further comprisingan encoder on said pedestal so that a distance moved along a peripheraldirection of said pipe member can be determined.
 39. The ultrasonicdetecting apparatus according to claim 35, further comprising an encoderon said pedestal so that a distance moved along a peripheral directionof said pipe member can be determined.
 40. The ultrasonic detectingapparatus according to any one of claims 31 to 35, wherein at least oneof a signal line of said transmitting element and a signal line of saidreceiving element is made of a shape memory alloy.
 41. The ultrasonicdetecting apparatus according to any one of claims 36 to 39, wherein atleast one of a signal line of said transmitting element, a signal lineof said receiving element and a signal line of said encoder is made of ashape memory alloy.